. >>> on our morning newscast terry mcsweeney will be live in boston with the latest on the investigation. one more note here tonight. after running more than 26 miles and hearing about the explosion in boston several runners today in boston at the marathon kept running straight to massachusetts general hospital so they could give blood, a glimmer of light on this otherwise dark day. >> we will leave you with a shot of the flags at the capitol. >>> tonight, a nbc news special report. after an awful day in boston, a bombing at the finish line of the boston marathon. there are mass casualties including children. the latest on what happened and where the investigation stands and including a search for a suspect as our nbc news special report gets under way. good evening. it is the best day every year in boston. the running of the boston marathon. it's a holiday, patriots day. the kids are home from school. the rocks play at fenway park today and they won and started off as a great day in boston. then, all eyes turned to the finish line at the marathon. at 2:50 this afternoon, 4:09 in to the